Pre-filled syringe cartridges are becoming more common because many medications, to be effective and even safe, require precise mixing at a well controlled mixing location, such as in a pharmaceutical manufacturing location. In a typical hospital or doctor's office it is usually not possible to mix certain medications accurately enough, since such locations do not normally have, nor can afford, the proper and precise mixing equipment required. As such, it is increasingly necessary to use such pre-filled syringe cartridges. Typically, however, the syringe enclosures used with such pre-filled syringe cartridges are not capable of retracting the needle or canula into a protective enclosure for the purposes of avoiding inadvertent, and potentially harmful, needle sticks.
One syringe device currently available includes an enclosure for use with a pre-filled syringe cartridge of medicine. This type of device is taught in U.S. Pat. No. 4,820,275 to Haber at al. on Apr. 11, 1989. While such a device does provide for the spring-influenced retraction of the needle and syringe, such retraction does not occur automatically upon the complete dispensing of the fluid contents of the cartridge. As such, it is possible for the needle to be withdrawn from the patient after delivery of the medication and still be unsafely exposed to others. Further, withdrawal of the needle by the medical practitioner is required, and such manual withdrawal of the needle, if done slowly and with lateral movement, can cause pain to the patient. While such a device might be better suited for dental work, it clearly has certain drawbacks when applied to more general medical fields.
Clearly, then, there is a need for an applicator device for use with a pre-filled syringe cartridge that, upon complete delivery of the contents of the cartridges, automatically retracts the syringe and needle safely into an inaccessible enclosure. Such a needed device could be used both for drawing fluid into the syringe, such as from a medicine bottle, and dispensing the fluid out of the syringe, such as while delivering an injection to a patient. Such a needed device would be relatively inexpensive to manufacture and easy to use. The present invention fulfills these needs and provides further related advantages.